The invention relates to gas turbine engines. More particularly, the invention relates to erosion coated blades.
Compressor blades operating in modern aircraft gas turbine engines are subject to erosion damage. The damage may be caused by ingestion of dirt and sand (e.g., from airport runways). Erosion damage shortens the operating life of blades because of changes in aerodynamic characteristics that reduce performance and reduce fatigue life.
One approach to extending blade life is to apply erosion-resistant coatings such as Co—WC and NiCr—CrC to those areas of the blade airfoil that are subject to the greatest erosion. However, these coatings have a deleterious effect on the fatigue properties of blade substrates, typically titanium and nickel based alloys. Consequently, the erosion coating is only applied to those areas of the airfoil where operating stresses do not exceed the reduced blade fatigue strength. It would be desirable to have ways to mitigate the deleterious effect erosion coatings have on the fatigue properties of the substrate.